Magnetic drive for centrifugal casting machines



May 19, 1931- v F. Mes. THOMAS 1,805,961

MAGNETIC DRIVE FOR CENTRIFUGAL CASTING MACHINES May 19, 1931. F. Mes. THOMAS 1,805,961

MAGNETIC DRIVE FOR CENTRIFUGAL CASTING MACHINES Filed Feb. '7, 1930 3 Sheets-Sheet 2 www AMaly 19, 1931. F. MCs. THOMAS MAGNETIC DRIVE FOR CENTRIFUGAL CASTING'-MACHINS Filed Feb. 7, 195D 5 Sheets-Sheet 3' I maf/zas Patented May 19, 1931 UNITED STATES FRANK MCS. THOMAS, OF EASTON, PENNSYLVANIA EAG'NETIC DRIVE FOR CENTRIFUGAL CAS'IIDTG- MACHINES Application filed February 7, 1930. Serial No. 426,622.

My said invention relates t'o centrifugal?l castin -machines of the type employing a cylin rical iask lined with sand which are supported in substantially horizontal position and rotated to properly distribute or position the metal to form the pipe or similar article. l In such machines it is desirable to supply the molten metal to the flask while the latter is being lslowly rotated to form a pool in the lower part of the flask of approximately even depth along the length thereof, whereupon the speed is suddenly increased or accelerated to a high degree, from 900 to 1200 R. P. M. which high speed is maintained for several minutes to distribute the metal and condense it by the centrifugal force and causing any impurities in the iron which are of less specific gravity, to travel towards the center of the ilask, or in other words, to the inner surface of the pipe formed by the machine. l

Great diliculty has heretofore been eX- perienced in securing durable and eiiicient means for securing such a variable drive.

The present invention vaims to provide a simple, economical, durableI and efcient means for rotating such asks which willfbe free from objections or defects present in prior machines of which I am aware.

The invention further aims to provide a machine which maybe operated with a minimum amount of power, and one in whichY the speed of rotation may be quickly accelerated to any desired degree without danger of vslippage or breaking of driving connections.

The invention further aims to provide an arrangement by which the amount of tractive force exerted by the driving roller or rollers on the iask may be increased proportionate to the power required.

With these and other-objects in view the invention includes the novel construction hereinafter described, the invention being defined b` the claims appended hereto.

An em diment of the invention is illustrated in the accompanying drawings in Fig. 2 is an end elevation looking from the right, Fig. 1.

Fig. 3 is an enlarged detail side elevation of a portion of the iask with one of the drive rollers and with the coil shown in section.

Fig. 4 is an end view of -a modified form using a simpler form of coil and adapted to be driven by a single motor applied to one roller shaft. f

Figs. 5 and 6 are detail views of a further modification.

Referring by reference character to these drawings the numeral 1 designates the flask or mold which is shown in a conventional manner only, for the reason that, except for the collars 1a hereinafter more specifically referred to, it may be of the ordinary or any desired construction. Such flasks are customarily formed of ferruginous material such as iron or steel, capable of b'eing'magnetized.

For supporting and driving the iiask I provide a plurality of pairs of cradle rolls 2 and 3 carried by shafts 4 and 5 journaled in suitable bearings 4a, removably bolted to the supporting frame members 6. In this form I have shown both shafts as-driven shafts, and for rotating them I prefer to provide electric motors 7 and 8 coupled to shafts by the customary couplings 6a and 7a.

For securing tractive lcontact between the drive rolls and flask whereby the latter is prevented from slipping and will be positively rotated with the drive rolls no matter what the amount of power applied, I provide means for causing these parts to be magnetically attracted towards each other during rotation.

rI his I preferably accomplish by providing the rollers with relatively deep grooves (two each) indicated respectively at 2a and 3a in which are located solenoids 9 of closed loop form the windin of which are connected with a source o electricity, such .solenoids being supported by rectangular frames including side bars 9a bolted to the tops of supports 6 and end bars 6b.

Preferably I connect the coils of the Ysolenoids in series with the amature coils of the motors 6 and `7 as indicated conventionally in Fig. 1 whereby, when the motor is stationary, the solenoids are inactive lua the flask capable of` being readily removed from the cradle rolls or replaced thereon; no top or presser rolls being required in my apparatus.

When the motor is started for slow rotation of the flask the current in the solenoid produces a magnetic attraction between the flask and rolls and holds the ask in position and causes it to be positively driven by the driv'- ing rolls. When it is necessary to accelerate the speed of the fiask the increased current supplied to the motor also increases the magnetic attraction thereby preventing` slippage between the driving rolls and flask and likewise preventing any jumping of the rapidly revolving flask upon or away from the cradle rolls. l

By this arrangement I secure relatively slight pressure of the flask on the driving rolls when the motor is developing small power and the speed is slow, with increase in Contact pressure at higher power and speed and in proportion thereto, while on stoppage of the machine magnetic attraction ceases as above stated.

To prevent endwise movement of the flask L relative to the cradle rolls the flask is provided with peripheral collars or raised portions of iron or steel, indicated at la which form tracks on which the cradle rolls bear. These tracks are of less width than the cradlerolls but bridge the solenoid recesses is passing out of or reducing the area of contact with the adjacent pole N is powerfully restrained by the magnetism in that particular pole, while the pole N on the opposite side,"having had its area of contact with the track increased, exerts less pull on the track which restores the relation shown in Fig. 3 where equilibrium is restored.

To enable the rolls to be removed without dismantling the solenoids and yet give the bearings ample support I provide the frame with open centered blocks 6c lying between the bearings and removably bolted in place. By taking out the blocks the bearings may be dropped down suiciently to enable the rolls to clear the solenoids.

In the form shown in Fig. 4c provision is4 a straight solenoid can be used as'indicated at 9m in dotted lines in said figure.

In the modification shown in Figs and 6 the rollers 2y and 3y are magnetized by iinduction from the magnet 10 which is venergized by the coil or solenoid 11. This gives a strong magnetic pull across the air gap between the magnet and rollers and also a` The following Vmay be mentioned as some j of the advantages arising from my invention. r

The ask is left free at both ends; v

Pressure on the bearings is reduced to the weight of the liask only;

There is no necessity for nice adjustment of rollers or accurate alinement. f

No change of rollers or change of spacing is required forvarious sizes of flasks;

The rollers may be mounted close to each other without danger of displacement of the flask by side motion; i

N o heavy friction and consequent wear such as occurs in machines using top vpressure rollers to secure pressure for tractive purposes;

Economical and rigid construction with low maintenance cost.;

Saving in power by elimination of constanty current used for magnetic clutches of the electric motor driven type now in use;

No cranking elfect in the driving of the flask; and

- No necessity of accurately sizing of flask and rollers.

contacting with the periphery of the flask,- and means forproducing magneticattractlon4 between said ask and driving roll.

' 2. In a centrifugal casting machine, a flask or mold of magnetizable material, a plurality of rolls for rotatably supporting said flask one or more of said rolls having means for driving the same, said driven roll having a pair of channels in its periphery, and a solenoid located in said channels adjacent the iask.

3. In a centrifugal casting machine, a flask or mold'of ma etizable material, a plurality of pairs o rolls supporting said flask, an electric motor for driving one of said,

rolls, and a solenoid for magnetizing said 4 driven roll having its coils connectedin se` ries with the armature coils of said motor.

4. In a centrifugal casting machine, a lask,`

cradle rolls for supporting said flask; one more of said rolls having means for rotating it and said flask havinga raised annular por# l tion of magnetizable material contacting las with said driven roll, and means for producing magnetic attraction between said driven roll and raised portion of the flask.

5. In a centrifugal casting machine, a flask having a plurality of raised peripheral roller tracks, a plurality of pairs of cradle rolls on Whichsaid tracks bear, said cradle rolls being slightly wider than said tracks, means for driving one or more rolls of each pair, and means for producingmagnetic attraction between the cradle rolls and said annular tracks.

6. In a centrifugal castingmachine a flask having a raised peripheral track,a pair of cradle rolls underlying said track one of said rolls being of greater width than the track and having peripheral channels, magnetizing coils located in said channels, means for driving said channeled roll, andl means for supplying electric current to magnetizing coils.

7. In a centrifugal casting machine, a ilask' having a raised peripheral track, a pair of cradle rolls underlying said track, one of said rolls being of greater width than the track and having peripheral channels, magnetizing coils located in the channels, an electric motor for driving said channeled roll, and a series connection between the motor armature and said magnetizing coil.

8. In a centrifugal casting machine, the combination with the flask of a pair'of coacting rolls thereunder,` said rolls having alined peripheral channels, a solenoid in the Jform of a closed loop lying in said channels and beneath said flask, means for driving one of saidcradle rolls, and means of energizing said solenoid.VV Y VV 9. In a centrifugal casting machine the combination with the flask of a pair of cradle rolls thereunder, including a driven roll, said driven roll and ask being of magnetizable material, and an electro-magnet located beneath said iask and between said cradle rolls said electro-magnet creating magnetic attraction between said flask and driven roll and exerting a magnetic pull upon the flask. 5'

10. Apparatus according to claim l in which the driving roll is driven b an electric motor and the means for pro ucing the said magnetic attraction is in circuit with the electric motor whereby the magnetic attraction increases with the speed of the motor, substantially as described.

11. In a centrifugal casting machine, a r0- tatable flask roller means for rotatably supporting said flask, said flask having a magnetizable track with which the roller means `contacts and means for producing magnetic .ment.

In testimony `Vwhereof, I ax my signature.

FRANK Mes. Taos. 

